I got this idea from Renaissance Magazine, but I did not like having to draft the full pattern. So I took a pattern I already had and made them into sea breeches, also called a sea petticoat.
• Pants pattern with two leg pieces, like for PJ's or scrubs. I used Simplicity 9802.
• Fabric- wool or canvas, about 2 ¾ yards.
• 1 yd of interfacing, I like muslin.
• Extra paper for pattern adjustments.
• Buttons or draw cord.
Take your waist measurement. Double this measurement, than divide it by four. Measures were the waist is on the pattern, omitting seam allowances. Expand the with of the pattern with paper. To do this, split the pattern down the middle. Insert paper, mark the extra with, and tape. This will give you nice full breeches. You could at this point measure where the breeches should come to, knee lenth or a bit longer. Cut off about two inches lower for a hem.
Next you will need to make a waist band and codpiece pattern. Skip this part if you are going to use a draw cord. The waistband is a rectangle that is your waist measurement plus two inches wide by three inches tall. Add a 5/8" seam allowances to all sides. (That's an extra 1 ¼ ".) The codpiece is a triangle with an 8" base and a height of 7", before seam allowances. I used a ½" seam allowance here.
Cut out your pieces, two of each pattern piece, of your fabric. Cut 1 waistband out of interfacing.
If you are going to make draw cord breeches, sew according to the pattern. Remember to make two holes in the front so you can draw the cord through before making the casing for said cord.
For waistband breeches-
Sew back crotch seam. Sew front crotch seam up to 5 ½" below waistline. Hem the fly opening. Sew the seam for the outer leg, and then sew the inseam.
Sew codpiece on all three sides, leaving an opening to turn. Trim and grade seams and clip corners. Turn codpiece inside out and hand stitch opening close. Add two buttonholes to the short edge of codpiece at each angle. Attach codpiece to breeches front. Center on seam with bottom point one to ½ inch below fly opening. Use a triangle shaped seam to attach codpiece.
Sew waistband on each three-inch side, one of the long sides, and two inches of the other side. Trim and grade seams and clip corners. Turn. Make a buttonhole on the tab.
Pleat breeches into waistband. Finish. Try on breeches and mark where buttons should go and mark hem.